1. Field of the Invention
The invention relates to a method for controlling operation of a refrigerator, and more particularly, to a method for controlling operation of a refrigerator compressor.
2. Background of the Related Art
A refrigerator is used for the long time fresh storage of food. In general, the refrigerator is provided with a food storage chamber for storing food in a frozen, or refrigerated state, and various components for carrying out a refrigerating cycle to cool down the food storage chamber. Among the key components for carrying out a refrigerating cycle, there are a compressor for compressing the refrigerant, a condenser for isobaric condensing of the compressed refrigerant, an expanding device for adiabatic expansion of the compressed refrigerant, and an evaporator for isobaric evaporation of the expanded refrigerant.
In the meantime, the refrigerator cools down the food storage chamber as the refrigerant circulates through the compressor, the condenser, the expanding device, the evaporator, and the compressor in succession. Once the food storage chamber is cooled down below a preset temperature as the compressor is driven for a time period, the compressor is stopped to stop circulation of the refrigerant, to stop the cooling down of the food storage chamber. If the compressor is stopped for a certain time period, the temperature of the food storage chamber rises, and if the temperature of the food storage chamber rises above a preset temperature, the compressor comes into operation, to cool down the food storage chamber again.
FIGS. 1 and 2 illustrate graphs each showing an example of a method for controlling operation of a compressor in a related art refrigerator carried out as above. Related art methods for controlling operation of a compressor in a refrigerator will be explained, with reference to FIGS. 1 and 2.
Referring to FIG. 1, the compressor is controlled to turn on/off repeatedly so that the temperature of the food storage chamber is within preset upper/lower temperature deviations (hereafter called as “ΔT”) from a preset optimal set temperature (hereafter called as “T”). That is, when the temperature of the food storage chamber reaches to an upper limit of T±ΔT, the compressor is turned on to drop the temperature of the food storage chamber, and when the temperature of the food storage chamber reaches to a lower limit of T±ΔT, the compressor is turned off to leave the temperature of the food storage chamber to rise, thereby controlling the temperature of the food storage chamber to be within T±ΔT. In this instance, the “T” is required for prevention of the compressor from being turned on/off too frequently.
In more detail, referring to FIG. 2, in the related art, a method for controlling turn on/off the compressor is used so that the temperature of the food storage chamber is to be within T±ΔT according to the upper/lower temperature deviations ΔT (1) fixed regardless of an external temperature variation with reference to an optimal set temperature ‘T’ required at the food storage chamber.
Consequently, while the turn on/off time period 2 is the shortest when an outside temperature is at a standard temperature (a temperature in a range of 20° C.˜30° C.), the turn on/off time period is long when the outside temperature is higher or lower then the standard temperature because the turn off time period 4 of the compressor is long when the outside temperature is lower than the standard temperature owing to a reduced heat load of the refrigerator, and the turn on time period 3 of the compressor is long when the outside temperature is higher than the standard temperature owing to an increased heat load of the refrigerator.
In the meantime, ‘T’ is inversely proportional to a freshness of food. That is, the higher the ‘T’, the lower the freshness of the food because the temperature of the food storage chamber varies in a great range with reference to ‘T’, and the lower the ‘T’, the higher the freshness of the food because the temperature of the food storage chamber varies in a small range with reference to ‘T’.
However, as explained, setting the ‘T’ too low for improvement of the freshness of the food causes too frequent turn on/off of the compressor, that degrades performance and lifetime of the compressor.